St. Elmo's fire
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St. Elmo's Fire is an electrical weather phenomenon in which visible plasma is created by a corona discharge originating from a grounded object in an atmospheric electric field (such as those generated by thunderstorms).
St. Elmo's fire is named after Erasmus of Formiae (also called St. Elmo), the patron saint of sailors (who sometimes held its appearance to be auspicious). Alternatively, Peter Gonzalez is said to be the St. Elmo after whom St. Elmo's fire has its name.
Ball lightning is often erroneously identified as St. Elmo's Fire. They are separate and distinct meteorological phenomena[1].
Observation
Physically, St. Elmo's fire is a bright pink-purple glow, appearing like fire in some circumstances, often in double or triple jets, from tall, sharply pointed structures such as masts, spires and chimneys, and on aircraft wings. Benjamin Franklin correctly observed in 1749 that it is electric in nature (see explanation below). It is said that St. Elmo's fire can also appear from the tips of cattle horns during a thunderstorm, or sharp objects in the middle of a tornado.
Scientific Explanation
Although referred to as "fire", St. Elmo's fire is in fact a low density, relatively cold plasma caused by a marked atmospheric electrical potential differences which exceed the dielectric breakdown value of air at around 3 megavolts per meter[citation needed].
Historical Observations
In ancient Greece, the appearance of a single one was called Helena and two were called Castor and Pollux. Occasionally, it was associated with the Greek element of Fire, as well as with one of Paracelsus's elementals, specifically the salamander, or, alternatively, with a similar creature referred to as an acthnici [2].
Welsh mariners knew it as canwyll yr ysbryd ("spirit-candles") or canwyll yr ysbryd glân ("candles of the Holy Ghost"), or the "candles of St. David"[3].
References to St. Elmo's fire, also known as "corposants" or "corpusants" from the Portuguese corpo santo[4] ("holy body"), can be found in the works of Julius Caesar (De Bello Africo, 47), Pliny the Elder (Naturalis Historia, book 2, par. 101) , Herman Melville, and Antonio Pigafetta's journal of his voyage with Ferdinand Magellan. St. Elmo's fire was a phenomenon described in The Lusiads.
Charles Darwin noted the effect while aboard the Beagle and wrote of the episode in a letter to J.S. Henslow that one night when the Beagle was anchored in the estuary of the Río de la Plata:
- "Everything was in flames, the sky with lightning, the water with luminous particles, and even the very masts were pointed with a blue flame."
Many Russian sailors have seen them throughout the years. To them, they are "Saint Nicholas" or "Saint Peter's lights"[3]. They were also sometimes called St. Helen's or St. Hermes' Fire, perhaps through linguistic confusion.[5]
In Fiction
There is a possible reference to St. Elmo's fire in Samuel Taylor Coleridge's The Rime of the Ancient Mariner:
- About, about, in reel and rout
- The death-fires danced at night;
- The water, like a witch's oils,
- Burnt green, and blue, and white.
Another reference made to St. Elmo's fire can be found in Ludovico Ariosto's epic poem Orlando Furioso. It is located in the 19th canto after a storm has punished the ship of Marfisa, Astolfo, Aquilant, Grifon, and others, for three straight days.
- "But now St. Elmo's fire appeared, which they had so longed for, it settled at the bows of a forestay, the masts and yards all being gone, and gave them hope of calmer airs."
In Herman Melville's Moby Dick
- "All the yardarms were tipped with a pallid fire, and touched at each tri-potential lightning rod with three tapering white flames, each of the three tall masts was silently burning in that sulphurous air, like gigantic wax tapers before an altar....in all my voyagings seldom have I heard a common oath when God's burning finger has been laid on the ship..."
In the comic book Tintin in Tibet by Herge, Captain Haddock's ice axe is hit by St. Elmo's fire.
References
- ^ Ball Lightning and Bead Lightning: Extreme Forms of Atmospheric Electricity, James Dale Barry, 1980.
- ^ The Elements and Their Inhabitants [1]
- ^ a b Folk-lore and folk-stories of Wales, The Sea, Lakes, Rivers and Wells, Marie Trevelyan, 1909.
- ^ The American Heritage Dictionary
- ^ http://inamidst.com/lights/wisp/brand1777
See also
External links
- - Video of St. Elmo's Fire (around 2:00 in the left window)
- http://www.islandnet.com/~see/weather/elements/stelmo.htm